Traces of dino blood, soft tissue found even in junk bones
Discovery gives scientists new places to search for clues to when warm-bloodedness evolved

DRIED BLOOD A scanning electron micrograph of a sliver of a theropod’s toe claw reveals oval-like structures that resemble the red blood cells seen in living birds. The colors correlate to density: less dense, carbon-based material appears red and denser mineralized material appears green.
S. Bertazzo et al/Nature Communications 2015